The pivotal event in 1815 that ended the Napoleonic Wars and led to the restoration of European monarchies was the Battle of Waterloo. This battle, fought on June 18, saw the defeat of Napoleon Bonaparte by a coalition army led by the Duke of Wellington and Gebhard Leberecht von Blücher. Following the defeat, Napoleon was exiled to Saint Helena, marking the end of his rule. The Congress of Vienna subsequently convened to reshape Europe, restoring many monarchies and establishing a balance of power to prevent future conflicts, significantly influencing European politics in the 19th century.